Author

Abstract

Biodiesel is a renewable fuel produced from triglycerides that can be used in existing diesel engines with little or no modification. The transesterification reaction used to produce biodiesel also produces a large amount of glycerin as a byproduct. In order to remain profitable, biodiesel manufacturers must sell the glycerin produced. However, the crude glycerin must be purified before selling because the solution contains unreacted methanol. The supply of glycerin also drastically exceeds industrial demand, reducing the possible profit from selling the byproduct. An alternative to the purification of glycerin is to directly reform the crude glycerin in supercritical water to produce hydrogen for use in energy applications. The process can handle the crude glycerin solution eliminating the need to go through the energy intensive separation purification and increasing the amount of transportation fuel that can be obtained from the triglycerides. The effect of pressure and water-to-carbon ratio on the supercritical water reformation of a crude glycerol solution was evaluated in an experimental study. The experimental study was conducted using a 0.1 L Haynesï¾® 282ï¾® alloy reactor keeping space time nominally constant at 45 seconds. The pressure was varied between 3250 and 3750 psig at a constant temperature of 600ï¾°C, a water-to-carbon ratio of 4.22:1 and using a crude glycerol solution that was 70 wt% glycerol and 30 wt% methanol. The water-to-carbon ratio was varied from 1.6:1 to 6.5:1 with constant pressure of 3500 psig, and temperatures of 550, 600, and 650ï¾°C using a crude glycerol solution that was 70 wt% glycerol and 30 wt% methanol.